A global potential energy surface for the H3+ molecule

A global two-valued ground-state potential for H3+ is constructed. The energy switching approach is used to combine different functional forms for three different energy regimes. The Born-Oppenheimer surface of Dinelli et al. [J. Chem. Phys. 103 (1995) 10433] is used for energies up to 20000 cm−1, for higher energies the many-body expansion of Sorbie and Murrell is fitted to ab initio calculations [Schinke et al,. J. Chem. Phys. 72 (1980) 3909], at large separations long-range terms are combined with accurate diatomic potentials. This produces an accurate global potential which represents all aspects of ground-state H3+ including the avoided crossing of the two surfaces and dissociation limits. This surface is suitable for studying spectroscopy, high-lying bound states and reaction dynamics.